1. Field of the Invention
The present invention relates generally to a liquid crystal display (LCD), and more particularly, to an LCD capable of being reduced by a whole size with a defective proportion thereof being minimized.
2. Description of the Related Art
Information processing devices presently in existence have been rapidly developed to have various architectures, various functions and faster information processing speeds. Information processed in these information processing devices has an electrical signal format. In order to visually confirm the information processed in the information processing device, a display device is typically provided as an interface.
Compared with the traditional cathode ray tube (CRT), liquid crystal displays (LCDs) have certain advantages such as lighter weight, small size, high resolution, and lower power consumption. In addition, LCDs are easily adapted to their intended environment, and are further able to display a full range of colors. Such advantages allow LCDs to replace the CRTs and to be spotlighted as a next generation display.
In general, LCDs employ two substrates that have, respectively, an electrode and a thin film transistor LCD (TFT-LCD) that switches power applied to the electrode. A TFT-LCD may include amorphous silicon TFT-LCD (a-Si TFT-LCD) or polycrystalline silicon TFT-LCD (poly-Si TFT-LCD). Poly-Si TFT-LCD has advantages of lower power consumption and lower price as compared to a-Si TFT-LCD. However, a drawback of the Poly-Si TFT-LCD is that it has a relatively complicated manufacturing process. Thus, poly-Si TFT-LCD is mainly used in small sized display devices such as mobile phones. On the other hand, amorphous-Si TFT-LCD is typically used in large screen-sized display devices such as notebook computers, LCD monitors, high definition (HD) television receivers, and the like.
FIG. 1 is a simplified schematic view showing a liquid crystal display panel of an a-Si TFT-LCD in accordance with the conventional art.
Referring to FIG. 1, a-Si TFT-LCD 50 includes an LCD panel 10 having pixel arrays, driving printed circuit boards 36 and 42 for providing driving signals to the LCD panel 10, and tape carrier packages (TCP) 32 and 38 that electrically connect the LCD panel 10 to the driving printed circuit boards 36 and 42.
The driving printed circuit boards 36 and 42 include a data printed circuit board 36 that drives a plurality of data lines formed in the LCD panel 10 and a gate printed circuit board 42 that drives a plurality of gate lines formed in the LCD panel 10. The data printed circuit board 36 is connected to terminals of the plurality of data lines through the data side TCP 32, and the gate printed circuit board 42 is connected to terminals of the plurality of gate lines through the gate side TCP 38.
The a-Si TFT-LCD has a data driving chip 34 formed on the data side TCP 32 in accordance with a COF (Chip-On-Film) technique, and a gate driving chip 40 also formed on the gate side TCP 38 by COF.
Recently, there have been many endeavors to decrease the number of assembly process steps by simultaneously forming the data driving circuit and the gate driving circuit, along with the pixel array on a glass substrate in both a-Si TFT-LCDs and poly-Si TFT-LCDs.
FIG. 2 is a simplified schematic view showing an a-Si TFT-LCD panel having data and gate driving chips are disposed thereon, in accordance with the conventional art.
Referring to FIG. 2, a-Si TFT-LCD 90 includes a glass substrate 60 having a display region 60a, in which the pixel array is formed, and a peripheral region 60b adjacent to the display region 60a. On the peripheral region 60b, a plurality of data driving chips 61 and a plurality of gate driving chips 62 are formed thereon. Each of the output terminals of the plurality of data driving chips 61 is connected to a corresponding data line of a plurality of data lines, and each of output terminals of the plurality of gate driving chips 62 is connected to corresponding gate line of a plurality of gate lines. Output terminals of the data and gate driving chips 61 and 62 are connected to an integrated printed circuit board (not shown) through a flexible printed circuit board 70.
The flexible printed circuit board 70 includes a control driving chip 71 and a common voltage generator 72. The control driving chip 71 provides a timing signal and an image data signal to the data driving chips 61 and gate driving chips 62, respectively. The common voltage generator 72 generates a common voltage.
The structure in which the data and gate driving chip 61 and 62 are formed on the glass substrate 60 decreases the cost of the LCD and also minimizes power consumption due to the integration of the driving circuits. However, when a plurality of driving chips is formed on a glass substrate as shown in FIG. 2, there are several problems that arise. First, when a plurality of driving chips is formed on a glass substrate, the defect proportion increases in proportion to the number of the chips formed on the substrate. As a result, the yield of the LCD decreases because the LCD module is not able to be used, even if a single chip among the plurality of driving chips is defective. Further, when the defect proportion increases, the process time of the LCD becomes longer, and the productivity thereof becomes lower.
Second, from the standpoint of instrumental structure, the resulting size of the LCD increases by mounting a plurality of chips on the glass substrate. This is because the number of patterns to be formed on the glass substrate increases as the total number of the chips increases, and thus the size of the LCD panel has to be increased in order to obtain space for forming the patterns. As a result, the desired high resolution may not be achieved in an LCD having a restricted size requirement.
Third, since the plurality of chips is formed in one side portion adjacent to the LCD panel, the structure of the LCD panel becomes lopsided, and the whole size of the LCD becomes larger.
Fourth, from the standpoint of image displaying characteristics through the LCD panel, a uniformity of image cannot be maintained due to contact resistance between the plurality of chips and the glass substrate.